The present invention relates to a supplemental cover for and method of reinforcing the case of softbound books, particularly paperback books and school workbooks.
The cases on paperback books are not nearly as durable as those on hardbound books. When used in a library environment, paperbacks quickly fall apart. Various self-adhesive supplemental covers or jackets have been proposed to extend the usefulness and life of paperbacks, as well as damaged hardbound books.
For maximum protection, the supplemental cover needs to be stiff in the area of the front and back covers of the book. At the same time, the area of the book's spine, and particularly the hinges, need to be sufficiently flexible to allow opening and closing of the book without cracking or breaking from repeated use. The spine of the book is typically not subject to major stress, so a stiff reinforcement is not needed or desirable. Also, because the spine flexes substantially and is of relatively small surface area, a stiff reinforcement tends to separate from the spine.
Various single piece jackets and supplemental covers have been used. They all suffer from the problems associated with differing book thicknesses. Some one-piece designs are stiff throughout, except for a series of reduced thickness hinge lines. It is then required that the thickness of the book match some pair of hinge lines out of those available. Other one-piece designs employ stiff portions joined by a flexible portion that is centered on the spine in use. The flexible portion is unadjustable, so that on a thin book, the flexible portion may extend from the spine to a large portion of the front and back covers. These large portions of the front and back covers are then not suitably reinforced.
A two-piece self-adhesive supplemental cover has been used which consists of two identical sheets. Each sheet is divided into a cover portion and a spine portion. The spine portion is of reduced thickness. The spine portions have to be overlapped on the spine. If the spine portions extend beyond the spine, they should be trimmed, or can overlap on the cover portion of the opposite sheet. When overlapped on the spine, the curvature of the spine when flexed and the relatively small adhesive contact area tend to cause the spine portions to pull loose from each other and from the spine. It is a cumbersome process to apply these covers.